With the development of smart phones, mobile phones are more and more important in people's daily life. The application of mobile phones is increasing, and the time people spend in using mobile phones every day is increasing. Under such a background, how to prolong the standby time of a mobile phone or reduce power consumption of a mobile phone becomes a more and more important issue. A proximity sensor for reducing power consumption of a mobile phone in a conversation is a good means of reducing power consumption.
Some smart phones such as an iphone now use a proximity sensor to reduce power consumption of the mobile phone in a conversation. The method for reducing power consumption may be as follows: when a call is originated or received, a proximity sensor is switched on periodically; after being switched on, the proximity sensor may emit infrared rays at intervals and use reflected infrared rays to determine whether the mobile phone approaches a human face; if the mobile phone approaches a human face, a backlight is turned off to reduce power consumption of the mobile phone; if the mobile phone leaves the human face, the backlight is turned on so that a user operates the mobile phone with the backlight. Therefore, when the user holds up the mobile phone and moves it to an ear to talk, the mobile phone turns off the backlight automatically to reduce power consumption of the mobile phone; in a conversation, when the user moves the mobile phone away from the ear to operate the mobile phone, the mobile phone turns on the backlight automatically. In this way, the power consumption of the mobile phone is reduced without affecting the user operation.
In the prior art, a proximity sensor in a conversation is switched on and off at fixed intervals, and emits an infrared ray at intervals to detect a distance between the mobile phone and the human face. For example, after the proximity sensor is switched on and continues for 50 ms, the proximity sensor is switched off, and then switched on again after a fixed interval (generally 200 ms). While being switched on, the proximity sensor emits infrared rays in the form of pulses. In the prior art, the interval from switching off the proximity sensor to switching on the proximity sensor is fixed. In order to detect in time whether the mobile phone approaches or leaves the human face, the interval is generally small. However, the small interval causes the proximity sensor to be frequently switched on and emit infrared rays, which increases power consumption of the mobile phone.